For attaching a poster, an advertisement or the like prepared by printing to a hard object to be attached, such as wall face, glass face, pillar, board, locker, bookshelf or the like, heretofore an adhesive agent, an adhesive tape or the like has been used. Recently, as such a poster, an advertisement or the like, those easily peelable in a reusable state even after use have been desired from the viewpoint of recycling materials. This is because, when they are attached with an adhesive agent or a double-sided adhesive tape, it is not easy to peel away and they are torn and become in a non-reusable state, it becomes difficult to recycle them as resources owing to remaining adhesive agent or pressure-sensitive adhesive agent, and finally there is a problem in that they may become wastes after once used. In addition, when a poster, an advertisement or the like is attached to an object to be attached such as wall face or pillar using an adhesive agent, an adhesive tape, or a double-sided adhesive tape, there arise problems in that the paste may remain after peeling them on the side of the object to be attached and the coating on the surface may peel away.
As a method of posting a poster or an advertisement not using an adhesive agent or an adhesive tape, use of an adsorption-type film that enables attaching by electrostatic force is proposed. For example, Patent References 1 and 2 propose an electrostatic adsorbability-given polyvinyl chloride film; and Patent Reference 3 proposes an electrostatic adsorbability-given polypropylene film.
However, though these films can be substitutes for adhesive agents, adhesive tapes and the like, as lacking in recordability, when they are used as display materials such as posters, they must be used after they are attached to a desired article. In addition, although a specific substance is incorporated in these films for keeping the electrostatic adsorbability, the films still have a defect that the durability thereof is insufficient.
Patent References 4, 5 and 6 propose a porous film composed of an electrostatically-adsorbable polymer. By making the film a porous film, the surface area of the film becomes large and the ability to hold electrified charges is enhanced. However, the porous film is formed according to a coating method, and therefore the polymer usable for it is limited to a polymer soluble in a solvent. In addition, since a polymer having a high moisture permeability is used and the pores formed therein are not closed pores, the film has defects in that the charge-retaining ability thereof varies depending on humidity and the electrostatic adsorbability thereof is also influenced by humidity.
Patent Reference 7 proposes a film that contains flat-shaped pores and has a high unipolar charge given to the inside thereof. The film produced according to the method has an advantage that the electrostatic adsorbability is high and the durability thereof is also high. However, the film has a defect in that, because of its high electrostatic adsorbability, the film may stick to rolls and others at the time of printing at a later stage thereby causing pattern misalignment or may catch dust or the like during printing and may thereby get dirty. Also, as in the cases of the films of Patent References 1 to 3, since the film does not have recordability, it also has a defect of insufficient ink adhesiveness.
Therefore, as disclosed in Patent Reference 8, the present inventors have developed a method of forming a laminate film by laminating a support subjected to antistatic treatment on a resin film having a recording layer through an adhesive agent and subsequently charging the laminate film (subjecting to an electrically charging treatment). However, since the charges imparted by the method are dispersed to both of the resin film and the support, it has been found that the method has a defect in that the electrostatic adsorbability of the resin film is not sufficiently enhanced.
Furthermore, since the films disclosed in Patent References 1 to 8 are all opaque, when they are attached to glass faces such as a window, print or the like cannot be clearly observed through the object to be attached and also viewing is impossible through the places to which the films are attached.